The present invention relates to a novel chemical-sensitization positive-working photoresist composition or, more particularly, to a chemical-sensitization positive-working photoresist composition capable of giving a patterned resist layer with high pattern resolution with high photosensitivity as well as an excellent cross sectional profile and heat resistance of the patterned resist layer and also having an advantage in respect of the stability of the latent image before development after pattern-wise exposure to actinic rays with little dependency on the nature of the substrate surface on which the photoresist layer is formed.
In the photolithographic patterning technology in the manufacture of various kinds of semiconductor devices, liquid crystal display panels and the like by utilizing a photoresist composition, it is a remarkable trend in recent years that so-called chemical-sensitization photoresist compositions are acquiring more and more prevalence among various types of photoresist compositions. The chemical-sensitization photoresist composition here implied is a photoresist composition containing an chemical agent capable of releasing an acid by the irradiation with actinic rays while the thus generated acid has a catalytic activity on the radiation-induced changes in the solubility of the resinous ingredient in an aqueous alkaline developer solution so that the photoresist composition containing even a relatively small amount of the acid-generating agent may have a high photosensitivity with a relatively small exposure dose.
Chemical-sensitization photoresist compositions can be classified into two types including the positive-working photoresist compositions and negative-working photoresist compositions depending on the solubility changes of the resist layer in an alkaline developer solution caused by the irradiation with actinic rays. The basic ingredients of a chemical-sensitization photoresist composition of each type include the above mentioned radiation-sensitive acid-generating agent and a film-forming resinous ingredient which causes a change in the solubility in an aqueous alkaline developer solution by interacting with the acid released from the acid-generating agent by the pattern-wise exposure of the resist layer to actinic rays.
The formulations of the chemical-sensitization positive- and negative-working photoresist compositions are different in the film-forming resinous ingredients. Namely, the chemical-sensitization positive-working photoresist composition usually contains, as the film-forming resinous ingredient, a polyhydroxystyrene resin which is substituted for the hydrogen atoms of a part of the hydroxyl groups by solubility-reducing protective groups such as tert-butoxycarbonyl groups, tetrahydropyranyl groups and the like while the film-forming resinous ingredient in the chemical-sensitization negative-working photoresist composition is usually a combination of a polyhydroxystyrene resin of which, optionally, a part of the hydroxyl groups are substituted for the hydroxyl hydrogen atoms by solubility-reducing protective groups mentioned above or a novolak resin with an acid-crosslinkable agent such as melamine resins, urea resins and the like.
Various attempts and proposals have been made heretofore for selection of the radiation-sensitive acid-generating agent used in the above described chemical-sensitization photoresist compositions including, for example, certain diazomethane compounds disclosed in Japanese Patent Kokai 3-103854, 4-210960 and 4-217249. The diazomethane compounds disclosed there and used in the formulation of a chemical-sensitization positive-working photoresist composition include bis(heteroarylsulfonyl) diazomethanes such as bis(imidazolylsulfonyl) diazomethane, bis(2-methylimidazolylsulfonyl) diazomethane, bis(benzoimidazolyl-2-sulfonyl) diazomethane, bis(benzoxazolyl-2-sulfonyl) diazomethane, bis(benzothiazolyl-2-sulfonyl) diazomethane and the like.
While a chemical-sensitization positive-working photoresist composition is basically a ternary composition comprising an alkali-soluble resin, an acetal-based solubility-reducing agent and an acid-generating agent, such a photoresist composition is not always quite satisfactory for the ultrafine patterning of a quarter-micron fineness recently under development in respects of the pattern resolution and influences of the standing waves on the cross sectional profile of the patterned resist layer to cause waviness on the side lines.
On the other hand, use of an aryl disulfone compound as an acid-generating agent is proposed in Japanese Patent Kokai 61-166544, 3-289658 and 5-94017. The photoresist compositions containing an acid-generating compound of this type, however, are not quite satisfactory in respects of pattern resolution, photosensitivity and stability of the latent image formed in the resist layer.